s
Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

TITANITE


TITANITE (Titanit—Titanite—“итанит) (Klaprpoth, M.H. 1795). The name reflects its titanium content. Another well-known name for it is sphéne, from Gk. “sphen” – a wedge, because of the shape of crystals.

Composition & Properties. Silicate – CaTi[O|SiO4], subclass orthosilicates, monoclinic system. Hardness 5-5.5. Density 3.4-3.6. Glass luster to greasy one. Cleavage in one direction. Fragile. Findings of titanite are represented mainly with separate crystals, more rarely with grained aggregates. The shape of crystals is often flattened, sometimes needle; twin clusters are typical. The size of crystals is usually up to 10 cm., sometimes more. Transparent to translucent. Color: brown, brownish-green, yellow, emerald-green, blue, rose-red, more rarely colorless. The type of coloring is zonal, and the outer segments are paler. In the level of dispersion and refraction titanite overcomes the most part of gemstones, it is inferior only to diamond, cassiterite and sphalerite. Titanite of apple-green hue was called ligurite, and its small yellow crystals – spinthére and séméline, non-transparent brownish one – lederite. Titanite of blue-violet hue, which depends of all kinds admixture, is called grothite, alshedite, eucolite-titanite; and when the content of (Y,Ce)2O3 is >12% – keilhauit or yttrotitanit. The intensity of green, brown and yellow color depends on the admixture of iron or chromium – for chrome-titanite. Rose variety with the admixture of MnO up to 4% is called greenovite or pseudarmone.

Deposits. Titanite is found at deposits of different genesis. In granite pegmatites, brownish crystals of titanite reach 25 cm, in alkali rocks – 6 cm, but gem-quality crystals are found mainly in alpine veins. In Russia, on the Kola Penin., in Khibiny, at the mines Kukisvumchorr and Umbozersky, in apatite-nepheline rock, titanite forms radial-rayed aggregates – suns up to 10 cm. in diameter. There was also found titanium-containing foyaite. This light colored rock is composed with lamellar crystals of orthoclase almost on 60%, and among these plates nepheline and honey-yellow titanite are. This rock is very beautiful when polished. Another rock, almost completely composed with titanite, is called sphenitite (sphenite). In the Murmansk Region, at the Kovdor deposit they found crystals of yellow titanite up to 5 cm. in length. In the Subpolar Urals Mts., in rock crystal veins of the deposits Dodo and Puiva, titanite is represented with crystals and their twin clusters, mainly of brownish-green color, up to 15 cm. long; and at the Central Patok deposit, they found violet-blue crystals with the admixture of yttrium. In the Middle Urals, at the Sarany deposit, Perm’ Region, they extract transparent green crystals of chromium-containing titanite up to 15 cm. long, including transparent ones up to 1.5x0.5 cm. Green titanite also is found at Verkhne-Neyvinskiy Zavod. In the South Urals, greenish-yellow crystals of titanite up to 2 cm. in size were extracted at the Akhmatovskaya and Eremeevskaya mines, in the region of Zlatoust; in the Ilmeny Mts. – at the Selyaninskie mines; and at the Rechnoye (Dzhaman-Akzhar) deposit, to the north-east from Orsk. In Pribaikalia, titanite was discovered in the region of Slyudyanka, at the Ulungui mine.

In Tadzhikistan, titanite, available for faceting, was discovered in the East Pamirs Mts., in nepheline-scapolite metasomatics, pegmatites and fluorite veins in the valley of the Zorburlyuk River, in the region of the Kukurt deposit. Its crystals of honey-yellow and yellow-brown hue reach 1 kg. In the south of Norway, at the deposits Kragerø, Telemark, and near Arendal, findings of red-brown variety keilhauit they registered, and in the Fauske region, Nordland, the size yellow green crystals reached 7 cm. In Finland, similar findings were described on the Parainen Is. (form. Pargas).Gem-quality yellow and green titanite up to 18 cm. long was found in alpine veins of Austria – at the Zillertal deposit, in Carinthia, and Felbertal, Salzburg. In Switzerland, at the Goms deposit, they found green titanite up to 10 cm. long, and also at the deposits Tavetsch and Binntal, Valais canton, up to 18 cm. In Germany, at a deposit by Laacher Lake, Rhineland-Palatiate, they found small transparent crystals of titanite – séméline. In Italy, near San Marcel, Piedmont, they found at first rose greenovite. In Namibia beautiful twin crystals of titanite were extracted at the Khamb deposit, near Khomas. On Madagascar, in alpine veins, the biggest crystals of titanite, up to 30 cm., were discovered in the north of the island, in the region of Iharaña (form. Vohémar); and near Androy, their size reached 15 cm. In Myanmar, gem-quality orange-brown titanite was extracted as additional material at placers in the region of Mogok; as well as in India – at the deposits of Tamil Nädu, near Mettür and Salem; in the Jammu and Kashmir State (disputed area), olive-green up to 2 cm. in the valley Tormiq River, near Astor.

In Canada, near Greenville, Québec Prov., they found emerald-green crystals up to 1.4x0.5 cm. in size, from which they made faceted stones up to 0.5 ct. In Ontario, at the Eganville deposit crystals of tntanite reached 40 kg. of weight; and 65x17x17 cm. dark brown titanite in the Lake Clear, Renfrew Dist., are found. In the U.S.A., in Colorado, at the Camp Bird mine, Urei Co., from transparent crystals of titanite they made faceted stones up to 18 ct. In the New York State, gem-quality titanite was extracted at the deposits Tilly Foster and Brewster, Patnam Co.; in Arkansas – at the Magnet Cove deposit, Hot Springs Co. In Brazil, in Minas Gerais, at the deposits Capelinha and Campod Boa, they found yellow-green and brownish-green crystals of titanite up to 12x4x5 cm. in size and even more, from which they made faceted stones up to 20 ct. In the Northern Mexico, at the El Rodeo, Sinaloa, and Ojos Negros deposit, near La Huerta, Baja California, they discovered crystals of titanite. In the same region at the deposits at Piño Solo, near El Álamo, and in the San Quintín, they found crystals of emerald-green and yellow-green chrome-titanite up to 16 cm. in size. From them faceted stones up to 3 ct. were made, and from brown crystals – faceted stones up to 14 ct.

Synonyms. Alshedite, after the Alsheda deposit, Småland, Sweden | Arpidelith, obs. | Aspidelite, from Gk. “aspis” – a shield | Castellite, after the Ital. researcher Castelli, which has described wine-yellow titanite in 1866. | Foyaite, after the La Foya Mt., Portugal | Gelbmenakerz, Germ. | Greenovite, after Greenaugh | Grothite, after the Germ. mineralogist P. Groth | Keilhauit, after the Norwegian geologist B.M. Kelhau | Lederite, after the Austrian consul Lederer | Ligurite, after the discovery location in the Liguria Prov., Italy | Menac, after the Menaccan deposit on the Cornwall Penin., Great Britain | Menac ore | Yellow menac ore | Prismatic titanic ore | Pictite, after the Fr. Geologist Picte | Séméline, from Lat. “séménlinen” – a linen seed, after the shape | Spinelline | Spinthére, from Gk. “spinthere” – a sparkle, after its bright luster.

Quality improvement. It is possible to weaken its dark brownish color with the thermal treating up to red, orange or green hue.

Cut Gems. Thick colored titanites display obvious dichroism: from colorless to greenish-yellow and to reddish-yellow. It should be taken into account in the process of faceting; a table should be placed on the right angle to the direction, where a stone is colorless or paled colored. In the faceted form the most valuable is emerald-green chrome-titanite, which displays diamond luster and bright effect of fire. Such stones are rarely more than 2-3 ct. Because of there flattened shape and rather small size of titanite crystals, faceted stones are not more than 5-10 ct., maximum up to 20 ct. From Indian material they made faceted stones up to 10 ct., from rough material from Madagascar – up to 15 ct., from Myanmar – separate stones were more than 20 ct. In the Smiths. Inst., Wash., they expose several faceted titanites: a golden one from Switzerland – 9.3 ct.; a brown one from the U.S.A., New York State – 8.5 ct. and a yellow-brown one from Mexico – 5.6 ct. A rare faceted red titanite, 4.95 ct. is kept in the Museum of Calgary, Canada. There is information that in one private collection a green titanite from Mexico, 63 ct. is kept.

Similarity. Titanite looks like axinite, vesuvianite, dravite, gold beryl, topaz, chrysoberyl, zircon, and scheelite.

Search